Refrigerator With Humidity-Optimized Storage Compartment

ABSTRACT

A refrigeration appliance includes a coolant circuit in which a speed-controlled compressor, an adjustable restrictor and a forced-air cooled first evaporator are connected in series. An evaporator chamber receives the first evaporator, a first storage compartment communicates with the evaporator chamber and a second storage compartment communicates with the evaporator chamber. A control unit or controller is configured to distribute cold air from the evaporator between the first and second storage compartments according to desired temperatures which can be adjusted differently for the first and the second storage compartments.

The present invention relates to a refrigeration appliance having a storage compartment whose humidity is optimized for a particular type of stored goods. The humidity prevailing in a storage compartment of a refrigeration appliance influences the achievable storage period. While high humidity values are desirable in particular for storing leafy or root vegetables in order to limit evaporation, for fruit, which naturally has an evaporation-limiting peel, and for packaged chilled goods, dry storage is more advantageous in order to prevent the formation of mold in particular.

Under standard operating conditions the evaporator of a refrigeration appliance is always colder than a storage compartment cooled by the evaporator. If the temperature difference is high enough for air from the storage compartment, in contact with the evaporator, to be cooled below the dew point, condensation water is deposited on the evaporator. With conventional refrigeration appliances with an intermittently operated compressor, at least during the operating times of the compressor it is reliably the case, so that the relative humidity in a storage compartment of such an appliance does not reach high values.

To maintain a high level of humidity in an energy efficient manner, the temperature difference between evaporator and storage compartment has to be minimized. This occurs by, firstly, a speed-controlled compressor being operated continuously with optimally exactly the power required to maintain a desired temperature in the storage compartment and the passage cross-section of an adjustable restrictor being adjusted such that the pressure in the evaporator matches the vapor pressure of the coolant at the evaporator temperature required to maintain the desired temperature of the storage compartment.

The unpublished German patent application 102015211960.2 describes a refrigeration appliance having a coolant circuit, in which a speed-controlled compressor, an adjustable restrictor and a forced-air cooled first evaporator are connected in series, a first storage compartment, which communicates with an evaporator chamber receiving the first evaporator, and a second storage compartment, in which the evaporation temperature, which is established in one of the evaporators in throughflow operation, can be controlled with the aid of controllable throttle vales connected up and downstream, and the humidity in the compartment cooled by this evaporator is determined by the temperature difference between the compartment and the evaporator.

The technology described in this earlier application is essentially only suitable for high-end refrigeration appliances since high numbers of controllable throttle valves and evaporators make manufacture of the appliance complex and expensive.

One object of the present invention is to provide a refrigeration appliance which enables an adjustment of the humidity in a storage compartment with simpler, less expensive means.

The object is achieved in that with a refrigeration appliance of the type mentioned in the introduction the second storage compartment communicates with the evaporator chamber and a control unit is configured to distribute cold air from the evaporator according to desired temperatures, which can be adjusted differently for the first and the second storage compartments, between the first and the second storage compartments. The invention makes use of the fact that with a forced-air cooled evaporator, the temperature, which is established in a storage compartment cooled by the evaporator, depends not only on the temperature of the evaporation, but also on the intensity of the exchange of air. Therefore, it is possible firstly to keep two storage compartments at different desired temperatures using a single evaporator by adjusting the exchange of air of the storage compartments with the evaporator to different intensities. With the warmer of the two compartments, the difference between compartment and evaporator temperature can be great and the air drying accordingly high; with the colder compartment, by contrast, the above-described conditions can be easily approximated for a high level of humidity.

The distribution of the cold air between the storage compartments can include each storage compartment being supplied with a particular portion, differing from zero, of the flow of cold air issuing from the evaporator chamber; however, it may also occur by time periods, in which this flow of cold air is completely supplied to the one storage compartment, and time periods, in which it is completely supplied to the other storage compartment, alternating with each other. The second alternative is the preferred one since it entails less mixing of the air in the storage compartments.

To be able to effectively limit the drying out of the second storage compartment, the control unit should be configured to limit a temperature difference between the evaporation temperature in the first evaporator and the desired temperature of the second storage compartment to a maximum of 7° C. This allows, in particular, operation of the first storage compartment as a standard refrigeration compartment whose desired temperature typically lies in an interval of 5-8° C., and of the second storage compartment as a chill compartment with a desired temperature of typically 1-4° C.

Conversely, the control unit can, however, also be configured to maintain a temperature difference between the evaporation temperature in the first evaporator and the desired temperature of the second storage compartment of a minimum of 20° C. to thereby achieve very dry storage conditions in the second compartment. This is possible in particular if the first compartment is temperature-controlled as a freezer compartment and the second compartment as a chill compartment.

The control unit can be configured to operate the speed-controlled compressor continuously.

To control the distribution of the cooling output of the evaporator between the first and the second storage compartments, a flap which can be adjusted by the control unit can be arranged in at least one passage between the evaporator chamber and the storage compartments.

A fan for circulating the air cooled at the evaporator can then jointly supply both compartments.

To limit mixing of air in the two compartments in the evaporator chamber, the flap preferably has two stable positions, wherein in one of these positions the passage between the evaporator chamber and the first storage compartment is open and between the evaporator chamber and the second storage compartment is closed, and in the other position the passage between the evaporator chamber and the first storage compartment is closed and between the evaporator chamber and the second storage compartment is open.

Alternatively, two fans having throughputs controllable by the control unit can be provided, of which one is accommodated in a passage between the evaporator chamber and the first storage compartment and the other in a passage between the evaporator chamber and the second storage compartment.

In this case the fans, in order to minimize mixing of air in the two storage compartments, should not operate simultaneously.

The pressure of the evaporation in the first evaporator will generally be higher than the intake pressure of the compressor. To exploit this pressure gradient, the coolant circuit can comprise a second evaporator, which is connected downstream of the first evaporator by way of a restrictor.

This second evaporator can cool at least one third storage compartment.

To be able to distribute the cooling output of the second evaporator flexibly according to need between the third and even a fourth storage compartment, the second evaporator can likewise be forced-air cooled and be accommodated in an evaporator chamber separate from the third storage compartment.

A control unit can be provided to control the exchange of air between the evaporator chamber and the third storage compartment and between the evaporator chamber and a fourth storage compartment using desired temperatures of the third and the fourth storage compartments.

The second and fourth storage compartments can be identical. Then, one and the same storage compartment can optionally be operated by loading with cold air from the first evaporator, in the case of high humidity, or by loading with cold air from the second evaporator, in the case of low humidity.

Alternatively, an adjustable partition can be provided between second and fourth storage compartments, which allows the sizes of the two storage compartments to be flexibly adjusted to the respective requirement.

The object is also achieved in that in the case of a refrigeration appliance having a coolant circuit, in which a compressor, a restrictor, a forced-air cooled first evaporator and a forced-air cooled second evaporator are connected in series, wherein the second evaporator is connected in series downstream of the first evaporator by way of a restrictor, first and second storage compartments and a control unit, which is configured to keep the first storage compartment at a first desired temperature by controlling the exchange of air between the first evaporator and the first storage compartment, the control unit is configured, moreover, to keep the second storage compartment at a second desired temperature optionally by the exchange of air with the first or the second evaporator, in order to be able to thereby adjust different values of the humidity in the second storage compartment independently of the desired temperature.

With this refrigeration appliance, a third storage compartment can be cooled by exchange of air with the second evaporator.

Further features and advantages of the invention result from the following description of exemplary embodiments with reference to the accompanying figures. In the drawings:

FIG. 1-4 show block diagrams of refrigeration appliances according to different embodiments of the invention.

FIG. 1 shows a block diagram of a refrigeration appliance according to a first embodiment of the invention. The refrigeration appliance is a combination appliance having warm, intermediate and cold compartments 1, 2 and 3, respectively, typically a standard refrigeration compartment, a chill compartment and a freezer compartment, which are cooled by a compression refrigeration machine 4. The compression refrigeration machine 4 comprises a speed-controlled compressor 5 and, in turn, a coolant line 8 running from a pressure connection 6 of the compressor 5 to its intake connection 7, a condenser 9, a first restrictor 10, a first evaporator 11, a second restrictor 12 and a second evaporator 13.

The evaporators 11, 13 are accommodated in evaporator chambers 14, 15. The evaporator chamber 14 communicates via feed lines 16, 17 and return lines 18, 19 with the standard refrigeration compartment 1 and the chill compartment 2. The two evaporator chambers 14, 15 each contain a fan 20, 21 for driving the exchange of air between the evaporator chambers 14, 15 and the connected storage compartments 1, 2, 3.

FIG. 1 shows a flap 22 at the connection point of the feed lines 16, 17 with the evaporator chamber 14; the flap 22 can be swiveled between two positions, in which it blocks one of the feed lines 16, 17 and unblocks the other one respectively. It is shown in an intermediate position, in which the two feed lines 16, 17 are open. Alternatively the flap could be arranged at the connection point between the return lines 18, 19 and the evaporator chamber 14 in order to block one of the return lines 18, 19 and unblock the other one respectively. According to further alternatives, two flaps could also be distributed among the feed lines 16, 17 or the return lines 18, 19, or the fan 20 could be replaced by two fans in the feed lines 16, 17 or the return lines 18, 19, which can be operated at speeds that are regulated independently of each other or, preferably, at different times respectively in order to control the exchanges of air between the evaporator chamber 14 and the compartments 1, 2 independently of each other respectively.

A temperature sensor (not shown in FIG. 1 for the sake of clarity) is provided on each storage compartment 1, 2, 3. The temperature sensors are connected to an electronic control unit 23. A desired temperature can be adjusted at the control unit 23 for each storage compartment 1, 2, 3. Using the measured values and the desired temperatures supplied by the temperature sensors, the control unit 23 controls the speed of the compressor 5, the position of the flap 22 as well as the degree of opening of at least one of the two restrictors 10, 12 or of both. If one of the two restrictors cannot be controlled, then this is preferably the first restrictor 10.

To cool standard refrigeration compartment 1 and chill compartment 2 simultaneously, the flow of cold air from the evaporator 11 must be distributed between the two compartments. This can be done by the flap 22 being in an intermediate position, in which it does not completely block any of the feed lines 16 and 17 and cold air flows from the evaporator 11 simultaneously to the two compartments 1, 2. However, this leads to mixing of the air masses, with different moisture levels in the compartments 1 and 2, in the evaporator chamber 14 and therefore ultimately to an outflow of humidity from the chill compartment 2. To minimize this it is preferred, in order to cool standard refrigeration compartment 1 and chill compartment 2, to switch the flap 22 between its two stop positions at regular intervals, so that—irrespective of the times at which the flap moves from one stop position into the other—of the two feed lines 16 and 17, one is always blocked.

Each switchover of the flap 22 leads to a quantity of air, which corresponds to the volume of the evaporator chamber 14, being exchanged between the compartments 1 and 2. To keep the effects of this exchange to a minimum, the period between two switchovers of the flap 22 should be greater than the quotient of volumes of the evaporator chamber 14 and throughput of the fan 20, preferably greater than ten times this quotient.

If the temperature of the chill compartment 2, but not that of the standard refrigeration compartments 1, is above the desired temperature, the control unit 23 extends the period, which the flap 22 spends in the position blocking the feed line 16, and reduces the time spent in the position blocking the feed line 17 accordingly, in order to intensify the exchange of air between the evaporator chamber 14 and the chill compartment 2. This can suffice as a correction measure if the cooling output of the evaporator 11 is sufficient for the two compartments 1, 2. If it is not, sooner or later both compartments 1, 2 are heated above their desired temperature. If this occurs, but the freezer compartment 3 does not exceed its desired temperature, then the restrictors 10, 12 or at least the restrictor 12 are triggered to reduce the pressure differential between the evaporators 11, 13 and thereby lower the evaporation temperature in the evaporator 11. If this leads to the desired temperature in the freezer compartment 3 being exceeded, then the speed of the compressor 5 has to be increased.

In this way, over the course of time, a temperature is established at the evaporator 11, which is just sufficiently below that of the chill compartment 2 to keep it at the desired temperature. Moisture from the air in the chill compartment 2 is only deposited on the evaporator 11 if the humidity in the chill compartment 2 is so high and the temperature difference from the evaporator 11 is so great that the air exceeds the dew point on cooling at the evaporator 11. The quantity of water vapor saturated in air reduces with a temperature decrease by 5° C. by about one third. Only if the relative humidity in the chill compartment 2 exceeds 67% can cooling by 5° C. at the evaporator 11 consequently lead to condensation, and it is not possible to fall below a relative humidity of 67%.

The temperature difference between the standard refrigeration compartment 1 and the evaporator 11 is significantly greater; the air in the standard refrigeration compartment 1 is correspondingly dried to a much greater degree by the evaporator 11. The user can take account of this by using the chill compartment 2 for chilled goods that are susceptible to drying out, and, in contrast, by using the standard refrigeration compartment 1 for chilled goods that are not sensitive to dry storage conditions or for packaged chilled goods.

In the embodiment of FIG. 1 the evaporator 13 cools only the freezer compartment 3.

A crisper 24 is also provided in the embodiment of FIG. 2. The desired temperature thereof can be adjusted to a level similar to that of the chill compartment 2. The evaporator chamber 15 communicates with the freezer compartment 3 and the crisper 24 via feed and return lines 25, 26, 27, 28 in a manner similar to the evaporator chamber 14 with the standard refrigeration compartment 1 and the chill compartment 2. FIG. 2 shows a flap 22 at the connection point of the feed lines 16, 17 with the evaporator chamber 14 and the feed lines 25, 26 with the evaporator chamber 15 respectively. These flaps 22 can each be replaced by the same alternatives as described with reference to FIG. 1.

The temperature difference between the desired temperature of the crisper 24 and the evaporator 13 is even greater than that between the desired temperature of the standard refrigeration compartment 1 and the evaporator 11; the air, which flows back from the evaporator chamber 15 to the crisper 24, is correspondingly dry. With a temperature difference between crisper 24 and evaporator 13 of 20° C., the humidity in the crisper can be kept below 25%.

In the embodiment of FIG. 3 the evaporator chamber 15 is connected via the feed and return lines 26, 28 to the same chill compartment 2 as the evaporator chamber 14. All feed lines 16, 17, 25, 26 can in each case be blocked by a flap 29. In the illustration in FIG. 3 the flaps 29 of the feed lines 17, 25 are open and those of the feed lines 16, 26 are closed, so that the fan 20 drives an air flow over the chill compartment 3, while the standard refrigeration compartment 1 is cut off from the supply of cold air, and the fan 21 supplies the freezer compartment 2 with cold air. Since the temperature of the evaporator 11 is only slightly below that of the chill compartment 2, the relative humidity in the chill compartment 2 can be high.

If, instead, the user desires a low level of humidity in the chill compartment 2, he can make a corresponding adjustment at the control unit 23 (not shown in FIG. 3 for the sake of clarity); this reacts by permanently closing the flap 29 of the feed line 17 in order to separate the chill compartment 2 from the evaporator 11, and instead periodically switches over the flaps 29 of the feed lines 25, 26 to distribute the cold air from the evaporator 13 between the freezer compartment 3 and the chill compartment 2. Due to the low temperature of the evaporator 13 dry air thus passes into the chill compartment 2. The control unit 23 constricts the passage cross-section of the restrictor 12, moreover, in order to take into account the shift in refrigeration requirement from the evaporator 14 to the evaporator 15.

The embodiment in FIG. 4 combines features of the embodiments in FIGS. 2 and 3. As in the case of FIG. 2 there is the chill compartment 2, which shares the evaporator 14 with the standard refrigeration compartment 1, and the crisper 24, which shares the evaporator 15 with the freezer compartment 3. Chill compartment 2 and crisper 24 are surrounded by a shared inner container 30; the boundary between them is formed by a partition 31. The partition 31 can be mounted in various positions in the inner container 30, for example in the same way as conventional shelves, by resting on supporting projections 32 on the partitions of the inner container 30. Therefore, if required, by changing the position of the partition 31, one of the compartments 2, 24 can be enlarged and the other reduced in size.

The partition 31 can also be removed, so that just a single storage compartment remains in the inner container 30. As described with reference to FIG. 3, this can then optionally be operated as a chill compartment with a high or low level of humidity.

REFERENCE NUMERALS

1 storage compartment (standard refrigeration compartment)

2 storage compartment (chill compartment)

3 storage compartment (freezer compartment)

4 compression refrigeration machine

5 compressor

6 pressure connection

7 suction connection

8 coolant line

9 liquefier

10 restrictor

11 evaporator

12 restrictor

13 evaporator

14 evaporator chamber

15 evaporator chamber

16 feed line

17 feed line

18 return line

19 return line

20 fan

21 fan

22 flap

23 control unit

24 crisper

25 feed line

26 feed line

27 return line

28 return line

29 flap

30 inner container

31 partition

32 supporting projection 

1.-15. (canceled)
 16. A refrigeration appliance, comprising: a speed-controlled compressor, an adjustable restrictor and a forced-air cooled first evaporator connected in series in a coolant circuit; an evaporator chamber receiving said first evaporator; a first storage compartment communicating with said evaporator chamber; a second storage compartment communicating with said evaporator chamber; and a control unit configured to distribute cold air from said evaporator between said first and second storage compartments according to desired temperatures being adjustable differently for said first and second storage compartments.
 17. The refrigeration appliance according to claim 16, wherein said control unit is configured to limit a temperature difference to a maximum of 7° C. between an evaporation temperature in said first evaporator and a desired temperature of said second storage compartment.
 18. The refrigeration appliance according to claim 16, wherein said control unit is configured to maintain a temperature difference of a minimum of 20° C. between an evaporation temperature in said first evaporator and a desired temperature of said second storage compartment.
 19. The refrigeration appliance according to claim 16, which further comprises at least one passage between said evaporator chamber and said storage compartments, and a flap disposed at said at least one passage, said flap being adjustable by said control unit.
 20. The refrigeration appliance according to claim 19, wherein: said flap has two stable positions; in one of said positions said passage between said evaporator chamber and said first storage compartment is open and said passage between said evaporator chamber and said second storage compartment is closed; and in another of said positions said passage between said evaporator chamber and said first storage compartment is closed and said passage between said evaporator chamber and said second storage compartment is open.
 21. The refrigeration appliance according to claim 19, which further comprises: a first fan accommodated in said passage between said evaporator chamber and said first storage compartment; and a second fan accommodated in said passage between said evaporator chamber and said second storage compartment; said fans having throughputs being controllable by said control unit.
 22. The refrigeration appliance according to claim 21, wherein said fans do not operate simultaneously.
 23. The refrigeration appliance according to claim 16, which further comprises a second evaporator disposed in said coolant circuit downstream of said first evaporator, and a restrictor disposed between said first and second evaporators.
 24. The refrigeration appliance according to claim 23, wherein said restrictor is an adjustable restrictor and another restrictor is connected upstream of said first evaporator.
 25. The refrigeration appliance according to claim 23, which further comprises a third storage compartment, said second evaporator cooling at least said third storage compartment.
 26. The refrigeration appliance according to claim 25, wherein said evaporator chamber is separate from said third storage compartment, and said second evaporator is forced-air cooled and is accommodated in said evaporator chamber.
 27. The refrigeration appliance according to claim 26, which further comprises: a fourth storage compartment; said control unit being configured to use desired temperatures of said third and fourth storage compartments to control: an exchange of air between said evaporator chamber and said third storage compartment, and an exchange of air between said evaporator chamber and said fourth storage compartment.
 28. The refrigeration appliance according to claim 27, wherein said second and fourth storage compartments are identical.
 29. The refrigeration appliance according to claim 27, which further comprises an adjustable partition provided between said second and fourth storage compartments.
 30. The refrigeration appliance according to claim 16, wherein said control unit is configured to continuously operate said speed-controlled compressor. 